One of the most commonly used tools in my photographic arsenal is the all purpose diffusion screen. I use it to soften light, create gradients and light fields or as a background. One of my current favorites is a metal framed 4' x 4' foot scrim with thick white artificial silk made by Matthews. I didn't think I would use it so much, being so large, but having borrowed it from a friend I really came to love it. The downside for me is the price. At just over $100 I couldn't really justify the cost, considering I want at least two of them. Time for a DIY alternative.